In an electric power system, switchgear is the combination of, for example, electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Switchgear can be used both to de-energize equipment to allow work to be done and to clear faults downstream. There are different types of switchgear.
In particular, switchgear may be a simple open-air isolator switch or it may be insulated by some other substance. An effective, although more costly, form of switchgear is the gas-insulated switchgear (GIS), where the conductors and contacts are insulated by pressurized gas, for example, sulfur hexafluoride gas (SF6). Other common types of switchgear are oil or vacuum insulated switchgear. The combination of equipment within the switchgear enclosure allows them to interrupt fault currents of thousands of amps.
Gas-insulated switchgear (GIS) generally handles medium to high voltages, for example, from 1 kV to 52 kV for medium-voltage classifications, and from 52 kV to 1200 kV for high voltage classifications. Gas-insulated switchgear (GIS) is a compact metal encapsulated switchgear consisting of components such as circuit-breakers and disconnectors, which can be safely operated in confined spaces.
Like all switchgear, GIS typically includes a mechanism for relieving overpressure generated by arcing faults. Conventional methods for relieving overpressure include, for example, bolt-on burst discs and rupture plates.